Inflammation is a non-specific first reaction mounted by the immune system in response to a perceived injury or threat. It is an innate defensive response, distinguished from the more precisely tailored adaptive responses of the immune system. Inflammation may work cooperatively with adaptive responses of the immune system, which develop more slowly but are more precisely targeted to a harmful agent such as a chemical or pathogen that may be causing localized injury.
Inflammation may be associated with infections, but it occurs in response to virtually any type of injury or threat, including physical trauma, cold, burns from radiation, heat or corrosive materials, chemical irritants, bacterial or viral pathogens, localized oxygen deprivation (ischemia) or reperfusion (sudden reinfusion of oxygen to ischemic tissue), and others. It includes the classic symptoms of redness, heat, swelling, and pain, and may be accompanied by decreased function of the inflamed organ or tissue. It is a generalized reaction involving several effects that may tend to combat an injurious agent that may be present at the site where an injury or threat was detected, or it may tend to contain the injury or threat to its initial location, to keep it from spreading rapidly.
Adaptive immune responses, on the other hand, develop when the body is exposed to a particular harmful agent: the cellular immune system ‘learns’ to recognize and attack the particular harmful agent by developing cell-mediated responses. Then, if that harmful agent persists long enough or returns later, the adaptive system recognizes the harmful agent and attacks it with a very specific response directed at the harmful agent itself. Such adaptive responses take time to develop, but are usually extremely specific, while the innate responses like inflammation involve more general changes in the affected tissue, and are not specifically targeted at an agent that is causing injury. These innate reactions involve recruitment of protective cells and substances to the area of the injury, and, unlike the adaptive responses, they typically occur rapidly.
Many methods to treat inflammation are known; however, all of them have limitations, and there are many causes of inflammation. Therefore, there is a need for new methods to combat inflammation associated with a variety of causes. The present invention provides such a method, using a protein factor known as T-4 immune stimulating factor (TISF).
TISF is a protein factor discovered from thymic tissue. It is about 50 kDa in size, with an isoelectric point of 6.5, and may be glycosylated. Its protein sequence has not been determined, but methods for its isolation and purification are disclosed in U.S. Pat. No. 5,616,554, to Beardsley, et al.
TISF has been reported to promote certain adaptive immune responses, even in subjects having a compromised immune system; thus TISF is known to be useful to treat certain types of infections that can be attacked by the adaptive immune system mechanisms. U.S. Pat. No. 5,616,554, for example, describes exposing subjects to influenza virus either with or without simultaneous treatment with TISF. The subjects were tested a few weeks later to evaluate their secondary cytotoxic killer cell response against influenza virus-infected cells, as a way to measure the effect of TISF on their cell-mediated immune (CMI) responses to the virus. Lymphocytes from subjects who had received TISF exhibited a 9-fold increase in killing activity relative to lymphocytes from control subjects, as measured by lysis of the target cells. TISF was also shown to increase antibody titers to hemagglutinin antigen (HA) in a mouse model. Thus subjects treated with TISF developed enhanced adaptive immune responses to influenza virus. This effect reduced the duration and/or severity of viral infections in animal models; however, there was no report of any direct effect on inflammation.
Subsequently, TISF has been shown to promote hematopoiesis, by stimulating the production or development of certain types of blood cells. Published U.S. Patent Application US2005-0107300. TISF has also been shown to be useful to treat certain T-Cell disorders, such as cutaneous T-cell lymphoma, by inducing apoptosis in aberrant lymphocytes. U.S. patent application Ser. No. 11/529,937, filed on Sep. 29, 2006, entitled “Methods to Treat T-Cell Disorders Using TISF”, to Beardsley. These effects of TISF are useful for treating certain types of disorders, but none of these effects discloses or suggests a direct or general means to treat inflammation.
Now, surprisingly, it has now been found that TISF directly reduces inflammation. The effect develops too rapidly to result from the stimulation of adaptive immune responses that was previously reported. It resulted in reduction in the severity of inflammation and associated disease effects within the first few days following treatment.
Anti-inflammatory activity was observed in ferrets exposed to influenza virus, and the effects were documented during days 1-4 post treatment. The ferret influenza model was selected as a recognized model that closely mimics human influenza infection with regard to both the sensitivity to infection and clinical response to treatment. The test was designed to further investigate the known effects of TISF for enhancing immune responses and promoting hematopoiesis, while also watching for other possible effects. Thus the general health, blood cell counts, and other parameters were monitored for the treated subjects, and viral load was also monitored. Unexpectedly, TISF was shown to reduce the general effects of the viral infection almost immediately, and it reduced the numbers of leukocytes (neutrophils) in nasal washes of treated ferrets. These nasal washes serve as a measure of upper respiratory inflammation in the treated animals. The effects of TISF on this parameter and on other indices of health status were noticeable within the first few days following treatment with TISF.
Inflammation is regulated by the levels of various cytokines, and it has become increasingly apparent that the effects of cytokines are influenced by a variety of factors and may thus be difficult to fully understand. For example, IL-10 is generally considered immunosuppressive and/or anti-inflammatory. However, IL-10 in combination with lipopolysaccharides can promote production of TNF, IL-6 and IL-1ra in certain blood cells. J. Adib-Conquy, et al., International Immunology, 11(5), 689-98 (1999). TNF is a pro-inflammatory cytokine, so the stimulation of TNF would be expected to have the opposite effect and to counteract the primary effects of IL-10 alone. This may explain why IL-10 appears to exhibit pro-inflammatory effects in some situations, while inhibiting inflammatory responses in others.
Without limiting the present invention by any theory of its operation, it is believed that TISF may combat inflammation at least in part by influencing the production of certain cytokines or of certain combinations of cytokines. It has been shown that TISF can stimulate production of certain cytokines, including IL-10, BM-CSF and IL-12, under conditions where it did not significantly affect the level of TNF-α. Thus the anti-inflammatory effect of TISF may result from its effects on levels of these and other cytokines.